1. Line two baking sheets with baking parchment. Set aside. Heat the milk until it is lukewarm. Add the fresh yeast and stir until dissolved completely.

2. In a large bowl add the flour, butter at room temperature in small pieces, egg yolk, sugar and salt. Add the yeast milk and knead all until you get a soft and smooth dough – takes about 5-8 minutes. Cover with a clean kitchen towel and let proof in a warm place for about 1 hour. The dough should double in size.

3. For the filling, mix water and sugar in a saucepan and bring to a boil. Add butter and let it melt. Add the ground hazelnuts and stir until you get a smooth mixture. Let it cool down.

4. Preheat the oven to 180°C (350°F). Remove the dough from the bowl and place on a floured surface. Knead once more for a short time and roll out to a rectangle with about 30x45cm. Cut into 6 stripes with 7,5x30cm each. Cut those stripes in half so you get 12 rectangles. Finally, cut those rectangles diagonally in half so you get 24 triangles with two long sides and a short one. Spread some filling on each triangle and roll up from the short side to the tip so you get a nice croissant, aka. »Hörnchen«. Place on the two baking sheets.

5. Mix the egg yolk with the heavy cream. Brush the croissants with this mixture and let them bake for 20 minutes. When done, take out of the oven and let cool on a rack. Dust with confectioners‘ sugar before serving.